It's official! Miley Cyrus and Patrick Schwarzenegger ARE dating -- and the marijuana-loving singer got to meet her boyfriend's mom, Maria Shriver last night!

After attending a Q&A for the film Still Alice, staring Kristen Stewart and Julianne Moore -- produced by Patrick's mom Maria -- the pair returned to Shriver's Brentwood home to celebrate.

Miley wore a cream-colored coat with matching crop top underneath and black leggings and carried a Chanel bag -- a bit more demure than her usual high-cut leotards and barely-there denim cut-offs.

The pair were whisked away in a chauffeur-driven car after the screening and the two 21 year-olds headed back to mom's.

Patrick first spoke about his crush on Miley in a 2011 interview with Details magazine, in which he said: "My eye is set on Miley."

The two were spotted just two weeks ago, coming out of what appeared to be Schwarzenegger's east LA apartment, close to USC where he attends school. Since then, the couple have kept a low profile and haven't seemed excited about going public with their relationship ... until now.

The screen of Shriver's film Still Alice was the pair's first public appearance together, seemingly cementing their relationship and officially "announcing" their boyfriend-girlfriend status.